Final answer:
The late Tang period under Emperor Wu-tsung is not characterized by the flourishing of Buddhism; rather, Wu-tsung was known for opposing Buddhism in favor of Taoism.
Step-by-step explanation:
One characteristic that NOT known to be true of the late Tang period under Emperor Wu-tsung is the promotion and flourishing of Buddhism as the state religion. The Tang period, particularly under Emperor Wu-tsung, is actually known for the suppression of Buddhism, particularly during a campaign to nationalize the wealth of the temples and reduce the influence of Buddhist monks who were exempt from taxes and military service. Historical records instead show that Emperor Wu-tsung was a devout Taoist and initiated the Great Anti-Buddhist Persecution around 845 AD.